1. Field of the Invention
The present invention relates to a toothbrush which pumps dentifrice material from a replaceable cartridge to the brush head. In particular, the invention provides means which increases the pumping efficiency and includes a cover having a slidable plug for sealing the opening in the brush head and pumping means during periods of non-use.
2. Description of the Prior Art
There are a variety of toothbrushes which store and dispense dentifrice material from the handle of the brush. One type of brush dispenses the dentifrice material at the base of the brush head where the bristles are attached, such as that described in U.S. Pat. No. 4,068,974. Another type dispenses dentifrice material directly onto the top of the brush surface as disclosed in U.S. Pat. No. 4,787,765. Most brushes store dentifrice material directly in a reservoir in the brush handle as typified by the brush shown in U.S. Pat. No. 4,269,207. Other brushes store the dentifrice material in a replaceable cartridge which is positioned in the reservoir. U.S. Pat. No. 4,116,570, as well as previously referenced U.S. Pat. Nos. 4,269,207, 4,068,974 and 4,787,765, describe brushes having this feature. Some of the cartridge toothbrushes contain a follower disc which advances in the cartridge as material is pumped therefrom and which serves as a seal to prevent backflow of material. This feature is described in U.S. Pat. Nos. 4,269,207 and 4,787,765. The prior art also includes toothbrushes that have detachable heads and which store dentifrice material in their handles. Exemplary patents in this regard include U.S. Pat. Nos. 4,269,207 and 4,332,497.
Various types of covers have been used with toothbrushes that store and dispense dentifrice material from the handle of the brush. A cover such as that shown in U.S. Pat. No. 4,521,128 protects the bristles and also plugs the opening which supplies dentifrice material to the brush head. The cover is secured to the brush head by inserting tabs on the cover into slots on the brush head. U.S. Pat. No. 4,332,497 discloses another type of cover which contains a stopper to seal the conduit which feeds dentifrice material to the brush head. The cover is placed over the brush head by inserting the brush handle through an opening in the cover and then closing a hinged portion of the cover over the brush head. The cover is not suitable for plugging a spout formed by a straight conduit which extends above the brush head base since the angular motion of the cover's stopper prevents its alignment with the spout opening. The type of cover shown in U.S. Pat. No. 4,221,492 encases the entire toothbrush, including the handle. This cover does not contain any component for protecting the opening which provides dentifrice material to the brush head.
The foregoing discussion illustrates some of the improvements which have been made in the design, structure, operation and protection of toothbrushes that store dentifrice material in their handles. However, the adhesive, paste-like consistency of the dentifrice materials used with the prior art bottom fed toothbrushes, has resulted in difficulties in consistently providing a smooth, void free flow of material. Also, the covers which have been used in conjunction with prior art bottom fed toothbrushes have shortcomings which effect the protection provided for the bristles and/or the efficiency for sealing the opening in the brush head platform particularly when the opening is extended by a spout. These difficulties and shortcomings associated with prior art bottom fed toothbrushes and their covers are more fully described below.
In any toothbrush which utilizes a replaceable cartridge for replenishing dentifrice material, continuous pumping after the cartridge is empty causes subsequent pumping problems and uneven material flow when the cartridge is replaced. A certain quantity of dentifrice material can still be pumped from the pump chamber, channels and other areas outside of the cartridge after it is empty. However, this causes the formation of voids in these places which results in inefficient pumping after the cartridge is replaced. For brushes that have piston-type pumping mechanisms, U.S. Pat. No. 5,062,728 utilizes a self-locking mechanism to prevent over-pumping when a cartridge reaches a near empty state. Such pumping mechanisms have sliding surfaces that are subject to leakage and contamination during brushing and cleaning. Also, the clogging of moving parts by dentifrice material impedes the spring-back function of the piston and leads to pumping failure. For this reason, piston-type pumping mechanisms which are used for dentifrice dispensing toothbrushes do not have broad consumer acceptability.
One way to avoid over-pumping involves the user's monitoring of the position of the follower disc through a viewing port in the handle. A viewing port as described in U.S. Pat. No. 4,787,765 allows the user to determine when the cartridge is nearly empty by observing the position of the follower disc. However, this approach does not ensure a failure-free operation of the toothbrush since the user may neglect to observe the position of the follower disc through the viewing port and may neglect to refrain from further pumping when the cartridge is empty.
The use of paste-like dentifrice materials in a bottom fed toothbrush has also resulted in difficulties which are caused by their tendency to dry out when exposed to air. This often causes the passageway which terminates in the brush head base to become clogged with dentifrice material that has dried out during periods of non use. The prior art has recognized and resolved this problem by providing a toothbrush cover with an attached plug that is inserted into the passageway opening thereby preventing the material therein from becoming dried out. However, the solution to this problem has created other problems. The covers of the prior art are cumbersome to place on the brush head to enclose all bristles without damaging some of the worn bristles that have become "fanned out" by wear. Worn bristles which have lost their stiffness and shape become angled and often are wedged out by the sidewall of the cover as it is positioned on the brush head. Also, while they effectively seal off the passageway which provides dentifrice material by restricting the flow of air thereto, some of the prior art covers have no means for ensuring adequate circulation of air to the brush head itself. Yet, the circulation of air through the bristles is essential for health reasons since they must be dried between uses prevent germ formation.
There is a need for a dentifrice dispensing toothbrush that does not utilize a piston type pumping mechanism but which efficiently overcomes problems that are caused by overpumping. More specifically, there is a need for a cartridge toothbrush which prevents further pumping when its cartridge is empty so that void formation in the dentifrice material is eliminated when a new cartridge is inserted. There is also a need for a bottom fed dentifrice dispensing toothbrush that has a cover that conveniently encloses all bristles, seals the conduit opening in the brush head base, permits air to freely circulate through the bristles to remove moisture and protects the pumping mechanism from accidental discharge of dentifrice material.
It is therefore an object of this invention to provide a bottom fed dentifrice dispensing toothbrush that does not use a piston type pumping mechanism and which has a replaceable cartridge which automatically hinders the pumping of the dentifrice material when the cartridge becomes empty.
It is a further object of the invention to provide a toothbrush which stores and pumps dentifrice material from its handle and which has a cover that conveniently and efficiently protects the bristles, pumping mechanism and seals the brush head opening.